Microbial Self-Healing Concrete: A Comprehensive Review of Mechanisms, Application, and Future Directions

Microbial self-healing concrete presents a sustainable strategy to enhance infrastructure durability while addressing critical environmental challenges. This review examines the role of bacteria, fungi, and microalgae in autonomously repairing cracks through calcium carbonate (CaCO3) precipitation. Particular emphasis is placed on mitigating ammonia emissions from urea-based processes and integrating waste-derived nutrients (e.g., corn steep liquor, tofu wastewater) to minimize reliance on synthetic additives. Implementation strategies, including direct mixing, dropping, vascular networks, and microencapsulation, are evaluated for their effectiveness across diverse environmental conditions, supported by field-scale evidence of crack healing and reduced permeability. Furthermore, the review highlights the potential of photosynthetic microbes to reduce CO2 emissions, directly supporting climate change mitigation and circular economy goals. Finally, critical barriers—including high initial costs and long-term stability—are assessed alongside future research priorities, such as screening extremophilic strains and optimizing nutrient cycles. Ultimately, this work offers actionable insights for integrating bioconcrete into sustainable infrastructure management, balancing structural resilience with ecological responsibility.